Use of plant defense elicitors for alleviating damage associated to the corn leafhopper

Abstract

This disclosure provides a method for alleviating the damaging effects of D. maidis in corn crops, which involves the use of plant defense elicitors such as jasmonates and salicylates.

Description

USE OF PLANT DEFENSE ELICITORS FOR ALLEVIATING DAMAGE ASSOCIATED TO THE CORN LEAFHOPPERCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Patent Application No. 63 / 665,861, filed June 28, 2024, the disclosure of which is hereby incorporated by reference in its entirety.FIELD OF THE INVENTION

[0002] The present invention is generally related to compositions and methods for alleviating the effect of pests which affect agronomically relevant crops. Particularly, the present invention is related to compositions and methods for the alleviation of drought stress caused by Dalbulus maidis attack in corn crops as well as the symptomatology associated with corn stunt disease complex. Even more particularly, the present invention is related to the use of plant defense elicitors for the alleviation of drought stress caused by Dalbulus maidis attack in corn crops and the symptomatology associated with com stunt disease complex.BACKGROUND

[0003] The corn leafhopper Dalbulus maidis (Hemiptera: Cicadellidae) is a phloem feeding species associated with maize agroecosystems. It damages maize plants directly, by removing sap with its piercing-sucking mouthparts and by laying endophytic eggs in the leaves; and indirectly, as a vector for four corn pathogens — two mollicutes (corn stunt spiroplasma CSS, and maize bushy stunt phytoplasma, MBSP) and two viruses (maize ray ado fino virus, MRFV, and maize striate mosaic virus, MSMV), which taken together are responsible for the corn stunt disease. It is the most important and widespread corn pest in the Neotropics being a primary corn pest due to changes in agronomic practices that favored the development of its populations. D. maidis is a specialist herbivore that has a long history of coevolution with plants belonging to the Zea genus, like maize(Zea mays L.) and its wild relatives, the teosintes (Zea spp. It feeds exclusively on maize and teosinte basing its foraging decisions on visual and olfactory cues.

[0004] Due to the climate change our planet is going through, D. maidis has spread in recent years to zones previously unaffected by it, generating an enormous increase in losses in corn production due to the corn stunt disease. In Argentina, the D. maidis plague outbreak was declared a national emergency in April 2024, with estimated losses exceeding USD 1.5 billion.

[0005] There is no particularly effective control treatment for D. maidis, with the most recommended strategy being the use of corn hybrids with inherent resistance to the pest and diseases transmitted by it. However, the availability of such hybrids may not be ensured for producers. On the other hand, neonicotinoid pesticides, metadiamides and isoxazolines have been reported to exhibit activity against D. maidis, but with limited efficacy, due to wax components on the insect’s cuticle and due to the presence of endophytic eggs that are not affected by non-systemic insecticides.

[0006] Correspondingly, there is an unmet need for effective methods and compositions for controlling D. maidis, its associated damage and the symptoms of the diseases transmitted by it in corn crops.

[0007] Plant resistance to biotic and abiotic stresses is regulated by salicylate-dependent defenses (Systemic acquired resistance, SAR) or ethylene- and jasmonate-dependent defenses (Induced systemic resistance, ISR). It is known that salicylates and / or jasmonates may be used as elicitors of plant defenses, thus increasing resistance of certain plants to different kinds of stress. However, these compounds usually exert antagonistic effects.

[0008] Chen et al. (2018) and Elazab et al. (2021) describe the use of jasmonates in the control of insect pests in Citrus and soybean plants. Similarly, Lee et al. (2022) describe the use of methyl salicylate for pest control in ornamental plant crops.

[0009] On the other hand, patent application WO2001026464 Al describes the use of salicylates for increasing the photosynthetic rate in plants, particularly in corn crops. ApplicationCN106234360A, relatedly, describes a growth-regulating composition comprising lentinan and jasmonic acid derivatives, which may be applied to corn.

[0010] However, the use of plant defense elicitors such as salicylates and jasmonates for controlling insect pests, particularly D. maidis, in corn crops, as well as for the alleviation of D. maidis-zssoc\&Q& damage and the symptomatology of corn stunt disease, is not known in the art.SUMMARY OF THE INVENTION

[0011] It is therefore an aspect of this invention to provide a method for alleviating the damaging effects of D. maidis in a corn crop, the method comprising applying a composition comprising a plant defense elicitor to the corn crop, wherein the plant defense elicitor is selected from the group comprising of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway.

[0012] Another aspect of this invention provides a method for alleviating the damaging effects of D. maidis in a corn crop, the method comprising applying a composition comprising a plant defense elicitor to the corn crop, wherein the plant defense elicitor is an activator of the jasmonic acid pathway.

[0013] In an embodiment of the invention, the plant defense elicitor is an activator of the jasmonic acid pathway. Preferably, the plant defense elicitor is methyl jasmonate. In some embodiments, the methyl jasmonate is applied to the corn crop at a dose from O.Olg / ha to 5 g / ha.

[0014] In another embodiment of the invention, the plant defense elicitor is an activator of the salicylic acid pathway. Preferably, the plant defense elicitor is salicylic acid. In some embodiments, the salicylic acid is applied to the corn crop at a dose from O.Olg / ha to 5 g / ha.

[0015] In an embodiment of the invention, the method comprises applying the plant defense elicitor to the corn crop more than once. Preferably, the dose of the plant defense elicitor is maintained within 0.01g / ha-10 g / ha depending on the number of applications. In certain embodiments, the dose of the plant defense elicitor is about 5.5 g / ha for 5 applications throughout the season.

[0016] In another embodiment of the invention, the corn crop does not produce Bacillus thuringiensis toxins.

[0017] It is another aspect of the present invention to provide a use of a composition comprising a plant defense elicitor and an agronomically acceptable carrier for alleviating the damaging effects of D. maidis in a corn crop, wherein the plant defense elicitor is selected from the group comprising of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway.

[0018] Another aspect of the present invention provides a use of a composition comprising a plant defense elicitor and an agronomically acceptable carrier for alleviating the damaging effects of D. maidis in a corn crop, wherein the plant defense elicitor is an activator of the jasmonic acid pathway.

[0019] In an embodiment of this aspect of the invention, the plant defense elicitor is present in the composition in a concentration from about 1 pM to about 1000 pM.

[0020] In an embodiment of this aspect of the invention, the plant defense elicitor is an activator of the jasmonic acid pathway. Preferably, the plant defense elicitor is methyl j asm onate. In some embodiments, the methyl jasmonate is present in the composition at a concentration from about 1 to about 100 pM.

[0021] In an embodiment of this aspect of the invention, the plant defense elicitor is an activator of the salicylic acid pathway. Preferably, the plant defense elicitor is salicylic acid. More preferably, the salicylic acid is present in the composition at a concentration from about 250 pM to about 750 p.Most preferably, the salicylic acid is present in the composition at a concentration from about 450 pM to about 550 pM.

[0022] In an embodiment of this aspect of the invention, the agronomically acceptable carrier is an aqueous solution comprising polysorbate. Preferably, the polysorbate is polysorbate 80. In some embodiments, the agronomically acceptable carrier is an aqueous solution comprising liquid silicone.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1. Size and spatial arrangement of experimental corn plots for field assay.

[0024] FIG. 2. Corn stunt disease severity scale used for field assay. 0= Without symptoms. 1= Only foliar symptoms. 2= Foliar symptoms plus reduction in internodes. 3= Foliar symptoms, severe reduction in internodes, several small corn ears.

[0025] FIG. 3. D. maidis abundance during the monitoring dates of field assay in Non-Bt com (A) and Bt corn (B), vertical lines indicate moments of spraying. (C) Total incidence in Non-Bt corn. (D) Total incidence in Bt corn.

[0026] FIG. 4. Chlorophyll content determined during field assay (Generalized Gamma Distribution Non-Bt: c2=5.89, df=2, P=0.05. Bt: c2=2.24, df=2, P=0.33).

[0027] FIG. 5. Plants height measured during field assay (Weibull distribution c2=19.297, df=5, P<0.01).

[0028] FIG. 6. Visual estimation for com stunting disease in com plots during field assay (Kruskal-Wallis K= 44.63, df=6, P<0.01).

[0029] FIG. 7. Yield obtained during the field assay was calculated based on the results from the production of the two central rows in each plot, totaling 15.6 square meters per treatment. This area was extrapolated to 10,000 square meters as kilograms per hectare (kg / ha).

[0030] FIG. 8. Parasitism rate (%) in D. maidis eggs determined during the field assay (Beta Binomial distribution c2=14.768, df=5, P=0.01).

[0031] FIG. 9. Dose optimization for assay #E1, Germplasm RFG22, aerial dry weight (A) and root dry weight (B).

[0032] FIG. 10. Dose optimization for assay #E2, Germplasm Brevant 22.6, aerial dry weight (A) and root dry weight (B).

[0033] FIG. 11. Dose optimization for assay #E3; Germplasm RFG 22, aerial dry weight (A) and root dry weight (B).

[0034] FIG. 12. Experimental design for assay #1.

[0035] FIG. 13. Effect of plant defense elicitors on height (A), (B) and yield (C) of D.maidis- infested corn crops.

[0036] FIG. 14. Experimental design for assay #2.

[0037] FIG. 15. Effect of plant defense elicitors on height (A) and yield (B) of D. / wz / zT / A-infested corn crops.

[0038] FIG. 16. Experimental design for assay #3.

[0039] FIG. 17. Effect of plant defense elicitors on height (A) and yield (B) of D.maidis-infested corn crops.

[0040] FIG. 18. Experimental design for assay #6.

[0041] FIG. 19. Effect of plant defense elicitors on height (A) and yield (B) of D.maidis-infested corn crops.

[0042] FIG. 20. Experimental design for assay #7.

[0043] FIG. 21. Effect of plant defense elicitors on height (A) and yield (B) of D.maidis-infested corn crops.

[0044] FIG. 22. Experimental design for assay #9.

[0045] FIG. 23. Effect of plant defense elicitors on height (A) and yield (B) of D. / wa / tZA-infested corn crops.

[0046] FIG. 24. Experimental design for assay #10.

[0047] FIG. 25. Effect of plant defense elicitors on height (A) and yield (B) of D.maidi s-infested corn crops.

[0048] FIG. 26. Dalbulus maidis counts in Non-Bt com (A) and Bt corn (B) during V6 stage. Bars indicate Sta Error. N=num of observations, Av= average, SD= Standard Deviation.

[0049] FIG. 27. Dalbulus maidis counts in Non-Bt com (A) and Bt corn (B) during V6 stage. Bars indicate Sta Error. N=num of observations, Av= average, SD= Standard Deviation.

[0050] FIG. 28. Visual assessment of stunting symptoms in Bt com (A) and Non-Bt corn (B).DETAILED DESCRIPTION OF THE INVENTION

[0051] All publications, patents and patent applications, including any drawings and appendices, are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

[0052] The following description includes information that may be useful in understanding the present disclosure. It is not an admission that any of the information provided herein is prior art or relevant to the presently embodimented disclosures, or that any publication specifically or implicitly referenced is prior art.

[0053] As used herein, the term "about" refers to plus or minus 10% of the referenced number, unless otherwise stated or otherwise evident by the context (such as when range would exceed 100% of a possible value or fall below 0% of a possible value). For example, reference to a value of "about 1%" means that the value may be present at any amount ranging from 0.9% to 1.1%. The term "about" also refers to plus or minus a day when referring to a length of time measured in days.

[0054] The term "a" or "an" refers to one or more of that entity; for example, "a gene" refers to one or more genes or at least one gene. As such, the terms "a" (or "an"), "one or more" and "at least one" are used interchangeably herein. In addition, reference to "an element" by the indefinite article "a" or "an" does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there is one and only one of the elements.

[0055] As used herein, "alleviating" or "altering" may refer to an increase or decrease relative to a control value.

[0056] As used herein, the term "elicitor" refers to any molecule that stimulates a response in a plant. Elicitors may be exogenous or endogenous, and may for example, activate the production of a secondary metabolite.

[0057] The present invention is based on the surprising capability of alleviating the damaging effects produced by the attack of Dalbulus maidis on com crops exhibited by certain plant defense elicitors.

[0058] The term “plant defense elicitors” should be understood as referring to compounds which activate natural synthetic pathways in plants which ameliorate the adverse effects of different types of biotic stress. Within the scope of the present description, the plant defense elicitors which may be used are those which activate either the so-called “jasmonic acid pathway” or the “salicylic acid pathway”.

[0059] The jasmonic acid and salicylic acid pathways, as known to those of skill in the art, are involved in complementary plant defense mechanisms named Induced Systemic Resistance (ISR) and Systemic Acquired Resistance (SAR), respectively. Both mechanisms may be activated in response to an initial attack by pathogens or certain chemical signals. This activation results in enhanced resistance throughout the entire plant, not just at the site of the initial attack. Therefore, both mechanisms are a form of priming where the plant becomes more resistant to future pathogenattacks. Each pathway involves the production and signaling of either jasmonic or salicylic acid, which are plant hormones that regulate numerous defense responses, such as the induction of defense-related genes, the production of toxic compounds against herbivores, and the production of antimicrobial compounds.

[0060] Throughout this description, reference may be made to plant defense elicitors which activate the jasmonic acid pathway. Such plant defense elicitors are typically either jasmonic acid or derivatives thereof, which as a whole are referred to as “jasmonates”. Correspondingly, throughout this description, the terms “plant defense elicitor which activates the jasmonic acid pathway”, “activator of the jasmonic acid pathway” and “jasmonate” are used interchangeably.

[0061] Throughout this description, reference may also be made to plant defense elicitors which activate the salicylate acid pathway. Such other plant defense elicitors are typically either salicylic acid or derivatives thereof, which as a whole are referred to as “salicylates”. Correspondingly, throughout this description, the terms “plant defense elicitor which activates the jasmonic acid pathway”, “activator of the salicylic acid pathway” and “salicylate” are used interchangeably.

[0062] Jasmonic acid and its methyl ester, methyl j asmonate (MeJA), collectively known as jasmonates, are octadecanoid-based compounds that occur naturally in plants. Jasmonic acid is produced by the roots of wheat seedlings, and by fungal microorganisms such as Botryodiplodia theobromae and Gibbrella fujikuroi, yeast (Saccharomyces cerevisiae), and pathogenic and non- pathogenic strains of Escherichia coli.

[0063] Useful derivatives of jasmonic acid and salicylic acid that may be useful in the practice of the present invention include esters, amides, glycosides and salts. Representative esters are compounds in which the carboxyl group of jasmonic acid or salicylic acid has been replaced with a - -COR group, where R is an —OR1group, in which R1is: an alkyl group, such as a Ci-Cs unbranched or branched alkyl group, e.g., a methyl, ethyl or propyl group; an alkenyl group, such as a C2-C8unbranched or branched alkenyl group; an alkynyl group, such as a C2-C8 unbranched or branched alkynyl group; an aryl group having, for example, 6 to 10 carbon atoms; or a heteroaryl group having, for example, 4 to 9 carbon atoms, wherein the heteroatoms in the heteroaryl group can be, for example, N, O, P, or S. Representative amides are compounds in which the carboxyl group of jasmonic acid or salicylic acid has been replaced with a --COR group, where R is an NR2R3group, in which R2and R3are independently: hydrogen; an alkyl group, such as a Ci-Cs unbranched or branched alkyl group, e.g., a methyl, ethyl or propyl group; an alkenyl group, such as a C2-C8 unbranched or branched alkenyl group; an alkynyl group, such as a C2-C8 unbranched or branched alkynyl group; an aryl group having, for example, 6 to 10 carbon atoms; or a heteroaryl group having, for example, 4 to 9 carbon atoms, wherein the heteroatoms in the heteroaryl group can be, for example, N, O, P, or S. Esters may be prepared by known methods, such as acid-catalyzed nucleophilic addition, wherein the carboxylic acid is reacted with an alcohol in the presence of a catalytic amount of a mineral acid. Amides may also be prepared by known methods, such as by reacting the carboxylic acid with the appropriate amine in the presence of a coupling agent such as di cyclohexyl carbodiimide (DCC), under neutral conditions. Suitable salts of jasmonic acid and salicylic acid include e.g., base addition salts. The bases that may be used as reagents to prepare metabolically acceptable base salts of these compounds include those derived from cations such as alkali metal cations (e.g., potassium and sodium) and alkaline earth metal cations (e.g., calcium and magnesium). These salts may be readily prepared by mixing together a solution of jasmonic acid or salicylic acid with a solution of the base. The salt may be precipitated from solution and be collected by filtration or may be recovered by other means such as by evaporation of the solvent.

[0064] The present inventors have found that plant defense elicitors which activate the jasmonic acid pathway are effective in alleviating the damaging effects of D. maidis in a corn crop. In someembodiments, plant defense elicitors which activate the salicylic acid pathway are effective in alleviating the damaging effects of D. maidis in a corn crop.

[0065] The present inventors have found that plant defense elicitors which activate the jasmonic acid pathway and plant defense elicitors which activate the salicylic acid pathway are, both, effective in alleviating the damaging effects of D. maidis in a corn crop. Correspondingly, provided herein is a a method for alleviating the damaging effects of D. maidis in a com crop, the method comprising applying a composition comprising a plant defense elicitor to the com crop, wherein the plant defense elicitor is selected from the group comprising of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway.

[0066] In some embodiments, the method comprises applying a composition comprising a plant defense elicitor to the corn crop, wherein the plant defense elicitor is selected from the group comprising of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway. In some embodiments, the method of treatment of a corn crop damaged with an infestation of D. maidis is provided, wherein the method comprises administration of a plant defense elicitor to the com crop, wherein the plant defense elicitor is an activator of a salicylic acid pathway in the corn crop.

[0067] In some further embodiments, also provided herein, is a method of treatment of a com crop damaged with an infestation of D. maidis, wherein the method comprises administration of a plant defense elicitor to the com crop, wherein the plant defense elicitor is an activator of a jasmonic acid pathway in the com crop.

[0068] A method for alleviating the damaging effects of Dalbulus maidis in a com crop, the method comprising: detecting an infection by Dalbulus maidis in the corn crop; andapplying an effective amount of a composition comprising a plant defense elicitor to the corn crop; wherein the plant defense elicitor is an activator of the salicylic acid pathway or an activator of the jasmonic acid pathway in the corn crop.

[0069] In some embodiments, the method(s) described herein comprises applying a composition comprising a plant defense elicitor to the corn crop, wherein the plant defense elicitor is an activator of the jasmonic acid pathway.

[0070] The expression “alleviating the damaging effects of D. maidis in a com crop” is to be understood broadly, as referring to a reduction in the measurable deleterious effects generated by an infestation of a corn crop with Z). maidis. Such measurable deleterious effects comprise both effects associated to the D. maidis feeding itself and effects associated to the corn stunt disease transmitted by the insect upon feeding. Correspondingly, alleviating the damaging effects of D. maidis in a com crop may comprise, for instance, an increase in the yield of the crop, an increase in the resistance to D. maidis-v Xa drought stress, an increase in plant height, among others, in comparison to a com crop infested with D. maidis and which has not been treated with a plant defense elicitor selected from the group comprising of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway.

[0071] It should be noted that the alleviation of the damaging effects of D. maidis in a corn crop achieved by the method of the invention is not directly related to a decrease in the incidence of the insect on the crop. The present inventors have thus surprisingly found that, even though the method of the invention does generate a repelling effect on D. maidis, thus decreasing the number of D. maidis individuals present in the treated corn crop, the damage alleviation effect obtained is much higher than the decrease in D. maidis incidence in the crop. Without adhering to any particular hypothesis, the method of the invention appears to generate an increase in the plant’s resistance tothe damaging effects of the insect and the corn stunt disease, independent of a potential repellent effect exerted on D. maidis.

[0072] In some embodiments, the plant defense elicitor may be prepared as a concentrate for industrial application and further dilution or as a fully diluted ready -to-apply composition. In other embodiments, the effective amount of the plant defense elicitor used to treat the plant, expressed in units of concentration, generally ranges from about 1 pM to about 100 pM. In some aspects, the composition comprises between about 1-10 pM, between about 10-20 pM, between about 20-30 pM, between about 30-40 pM, between about 40-50 pM, between about 50-60 pM, between about 60-70 pM, between about 70-80 pM, between about 80-90 pM, or between about 90-100 pM of a plant defense elicitor. The effective amount of the plant defense elicitor, however, depends on the dilution in the field. The effective amount of the plant defense elicitor, however, may be obtained by a suitable dosage response assay, preferably, in a greenhouse and / or field study.

[0073] In an embodiment of the invention, the plant defense elicitor is an activator of the jasmonic acid pathway. Preferably, the plant defense elicitor is methyl jasmonate.

[0074] In another embodiment of the invention, the plant defense elicitor is an activator of the salicylic acid pathway. Preferably, the plant defense elicitor is salicylic acid.

[0075] The plant defense elicitor should be applied to the corn crop at a dose which exerts an effective alleviation of the damaging effects of D. maidis on the crop, without producing any adverse or phytotoxic effect thereon. For instance, the plant defense elicitor may be applied to the corn crop at a dose from 0.01 g / ha to 5 g / ha. In some aspects, the plant defense elicitor may be applied to the corn crop at a dose from about O.Olg / ha -0.1 g / ha, between about O.lg / ha -0.5 g / ha, between about 0.5-1 g / ha, between about Ig / ha -1.5 g / ha, between about 1.5 g / ha -2 g / ha, between about 2 g / ha-2.5 g / ha, or between about 2.5g / ha -3 g / ha. In some aspects, the plant defense elicitor may be applied to the com crop at a dose from about O.Olg / ha -0.1 g / ha, about O. lg / ha -0.5 g / ha, about 0.5-1 g / ha,about Ig / ha -1.5 g / ha, about 1.5 g / ha -2 g / ha, about 2 g / ha-2.5 g / ha, or about 2.5g / ha -3 g / ha. In some aspects, the plant defense elicitor may be applied to the com crop at a dose from about O.Olg / ha, 0.02 g / ha, 0.03 g / ha, 0.04 g / ha, 0 / 05 g / ha, 0.06 g / ha, 0.07 g / ha, 0.08 g / ha, 0.09 g / ha, 0.1 g / ha, 0.2 g / ha, 0.3 g / ha, 0.4 g / ha, 0.5 g / ha, 0.6g / ha, 0.7 g / ha, 0.8 g / ha, 0.9 g / ha, 1 g / ha, 1.1 g / ha, 1.2 g / ha, 1.3 g / ha, 1.4 g / ha, 1.5 g / ha, 1.6 g / ha, 1.7 g / ha, 1.8 g / ha, 1.9 g / ha, 2 g / ha, 2.1 g / ha, 2.2 g / ha, 2.3 g / ha, 2.4 g / ha, 2.5 g / ha, 2.6 g / ha, 2.7 g / ha, 2.8 g / ha, 2.9 g / ha, or 3 g / ha.

[0076] In a preferred embodiment, the plant defense elicitor is methyl jasmonate, and it is applied to the com crop at a dose from 0.01 g / ha to 5 g / ha, more preferably from 0.5 g / ha to 1.1 g / ha.

[0077] In an embodiment of method, methyl jasmonate is present in the composition at a concentration from about 1 to about 500 pM. In some aspects, the composition comprises about 1 pM, about 10 pM, about 15 pM, about 20 pM, 25 pM, about 50 pM, 95 pM, 135 pM, 175 pM, 210 pM, 255 pM, 295 pM, 340 pM, 385 pM, 450 pM or 500 pM of methyl jasmonate, including all ranges and subranges therebetween. In some embodiments, methyl jasmonate is present in the composition at a concentration from about 1 pM to about 25 pM. In some embodiments, methyl jasmonate is present in the composition at a concentration from about 25 pM to about 100 pM.

[0078] In another embodiment of method, salicylic acid is present in the composition at a concentration from about 250 pM to about 750 pM. In some aspects, the composition comprises about 250 pM, 300 pM, 350 pM, 400 pM, 450 pM, 500 pM, 550 pM, 600 pM, 650 pM, 700 pM or 750 pM of salicylic acid, including all ranges and subranges therebetween. More preferably, the salicylic acid is present in the composition at a concentration from about 450 pM to about 550 pM.

[0079] The method of the invention may comprise several applications of the plant defense elicitor to the corn crop. The dose administered in each subsequent application may be varied to account for the growth of the corn plants and the incidence level of D. maidis in the crop.Correspondingly, in an embodiment of the invention, the dose of the plant defense elicitor is increased with each application throughout the plant growth stages of the crop.

[0080] The method of the present invention may be applied to crops of any variety of corn. However, the inventors have surprisingly found that the method of the invention exhibits a particularly high capability of alleviating the damaging effects of D. maidis when the corn crop does not produce Bacillus thuringiensis toxins.

[0081] As known to a person of skill in the art, corn plants may be genetically modified to produce certain B. thuringiensis proteins which work as toxins against some insect pests, such as those of the Spodoptera genus. Throughout this description, corn crops which are genetically modified to produce B. thuringiensis toxins (also known as Bt-toxins) may be referred to as “Bt corn”. Similarly, corn crops which have not been genetically modified to produce Bt-toxins may be referred to as “Non-Bt corn”.

[0082] Correspondingly, in another embodiment of the invention, the com crop which the composition comprising the plant defense elicitor is applied to does not produce B. thuringiensis toxins.

[0083] The plant defense elicitor applied to the com crop must be formulated in a composition which is appropriate for its application to said corn crop for the intended use of alleviating the damaging effects of D. maidis.

[0084] Correspondingly, it is another aspect of the present invention to provide a use of a composition comprising a plant defense elicitor and an agronomically acceptable carrier for alleviating the damaging effects of D. maidis in a corn crop, wherein the plant defense elicitor is selected from the group consisting of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway.

[0085] The concentration of the plant defense elicitor should be suitable for the stable storage of the composition while being able to provide an effective activation of the corresponding metabolic pathway so as to generate an effective alleviation of D. / zzcz / t / z.s-associated damaging effects. In an embodiment of this aspect of the invention the plant defense elicitor is present in the composition in a concentration from about 1 pM to about 1000 pM.

[0086] In an embodiment of this aspect of the invention, the plant defense elicitor is an activator of the jasmonic acid pathway. Preferably, the plant defense elicitor is methyl j asm onate. More preferably, the methyl jasmonate is present in the composition at a concentration from about 1 to about 25 pM. Most preferably, the methyl jasmonate is present in the composition at a concentration from about 1 pM to about 15 pM.

[0087] In another embodiment of this aspect of the invention, the plant defense elicitor is an activator of the salicylic acid pathway. Preferably, the plant defense elicitor is salicylic acid. More preferably, the salicylic acid is present in the composition at a concentration from about 250 pM to about 750 pM. Most preferably, the salicylic acid is present in the composition at a concentration from about 450 pM to about 550 pM.

[0088] The composition should be applied at a dose such that a proper damage-alleviation effect is achieved in the treated crop, without producing any phytotoxic effects thereto, depending on the plant defense elicitor used, the concentration thereof, and external aspects such as environmental conditions, the severity of theZ). maidis infestation, etc. In an embodiment of this aspect of the invention, the composition is applied to the crop at an amount from 50 to 1500 L / ha. In certain embodiments, the composition is applied to the crop at an amount of about 10 to 100 L / ha in each application. In some aspects, the composition is applied to the crop at an amount of about 10 to 20 L / ha, about 20 to 30 L / ha, about 30 to 40 L / ha, about 40 to 50 L / ha, about 50 to 60 L / ha, about 60 to 70 L / ha, about 70 to 80 L / ha, about 80 to 90 L / ha, about 90 to 100 L / ha in each application.

[0089] Plants may be treated with the plant defense elicitor in several ways but preferably via spraying or dripping. Spray and drip treatment may be conducted by formulating an effective amount of the plant defense elicitor in an agriculturally acceptable carrier, typically aqueous in nature, and spraying or dripping the composition onto the plant via a continuous treating system (which is calibrated to apply treatment at a predefined rate in proportion to the continuous flow of plant), such as a drum-type of treater. These methods advantageously employ relatively small volumes of carrier so as to allow for relatively fast drying of the treated plant. In this fashion, large volumes of plants can be efficiently treated. Batch systems, in which a predetermined batch size of plant and plant defense elicitor compositions are delivered into a mixer, may also be employed.

[0090] In certain embodiments, the application is to an aerial part of the com crop.

[0091] In another embodiment, the treatment entails spraying the plants. Spraying typically entails use of an aqueous solution containing the plant defense elicitor. For example, plants can be sprayed for about 100 milliseconds to about 5 seconds (e.g., for at least 100 milliseconds, 500 milliseconds, 1 second, 2 seconds, 3 seconds, 4 seconds, 5 seconds).

[0092] In some embodiments of this method, a plant defense elicitor of the disclosure is suitable for application directly to a pest or pathogen. In some embodiments, a plant defense elicitor of the disclosure is suitable for application to a pest or pathogen in vitro for the reduction or treatment thereof.

[0093] The composition is intended to be administered to the corn crop by foliar application. Correspondingly, the composition is liquid, and thus the agronomically acceptable carrier of the composition is a liquid carrier able to dissolve or suspend the plant defense elicitor for a proper application thereof to the com crop.

[0094] Typically, the agronomically acceptable carrier is an aqueous solution wherein the plant defense elicitor is dissolved. Such an aqueous solution may comprise additional componentscommonly used in compositions for agronomical use, such as surfactants, pH regulators, stabilizers, anti -foaming agents, etc.

[0095] In an embodiment of this aspect of the invention, the agronomically acceptable carrier is an aqueous solution comprising a surfactant. Such a surfactant works as an emulsifier for facilitating the penetration of plant defense elicitor into the plants. Several known surfactants may be used for this purpose, such as, without limitation, polysorbates, polyglycols as well as esters thereof, poloxamers, etc.

[0096] In a preferred embodiment of this aspect of the invention, the agronomically acceptable carrier is an aqueous solution comprising polysorbate. More preferably, the polysorbate is polysorbate 80. In some embodiments, the agronomically acceptable carrier is an aqueous solution comprising liquid silicone. It is within the knowledge of a person of skill in the art to optimize the concentration of the polysorbate according to this embodiment of the invention. For instance, the polysorbate may be present in the composition in a concentration from about 0.01% w / v to about 0.1% w / v, based on the total volume of the composition. In a particularly preferred embodiment of this aspect of the invention, the agronomically acceptable carrier is an aqueous solution comprising polysorbate 80 in a concentration of about 0.05% w / v, based on the total volume of the composition.

[0097] In some embodiments, pests are alleviated from contacting plants for at least 1 day after application. In some aspects, pests are alleviated from contacting plants for at least 2 days after application. In some aspects, pests are alleviated from contacting plants for at least 3 days after application. In some aspects, pests are alleviated from contacting plants for at least 1 week after application. In some aspects, pests are alleviated from contacting plants for more than 1 week after application (e.g., for at least 8 days, or at least 9 days, or at least 10 days or at least 11 days, or longer).

[0098] Another aspect of the invention is a method to alleviate the damaging effects of Dalbulus maidis in a corn crop, thereby limiting or reducing the damage compared to an untreated control.

[0099] In yet another aspect of the invention, the method for alleviating the damaging effects of Dalbulus maidis in a corn crop, the method comprising: applying a composition comprising a plant defense elicitor to the corn crop, wherein the plant defense elicitor is selected from the group comprising of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway, wherein there is change in the height of the corn crop by at least 5% after the application of the composition.

[0100] In some embodiments, the height is at least 5% greater than the height in the absence of the plant defense elicitor of the invention. The height may be at least 10% greater, at least 20% greater, at least 30% greater, at least 40% greater or at least 50% greater. In some embodiments, the height is from about 10 % to about 50 % greater than the height in the absence of the plant defense elicitor of the invention.

[0101] In yet another aspect of the invention, the method for alleviating the damaging effects of Dalbulus maidis in a corn crop, the method comprising: applying a composition comprising a plant defense elicitor to the corn crop, wherein the plant defense elicitor is selected from the group comprising of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway, wherein there is change in the yield of the com crop by at least 10% after the application of the composition.

[0102] In some embodiments, the yield is at least 5% greater than the yield in the absence of the plant defense elicitor, at least 10% greater than the yield in the absence of the plant defense elicitor of the invention. The yield may be at least 20% greater, at least 30% greater, at least 40% greater or at least 50% greater. In some embodiments, the yield is from about 10% to about 50 % greater than the yield in the absence of the plant defense elicitor of the invention.

[0103] Another aspect of the invention is use of a composition comprising a plant defense elicitor and an agronomically acceptable carrier for alleviating the damaging effects of D. maidis in a corn crop, wherein the plant defense elicitor is selected from the group comprising of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway.

[0104] In some embodiments, the plant defense elicitor is present in the composition in a concentration from about 1 pM to about 1000 pM. In some embodiments, the plant defense elicitor is an activator of the jasmonic acid pathway. In some embodiments, the plant defense elicitor is methyl jasmonate. In some embodiments, methyl j asmonate is present in the composition at a concentration from about 1 to about 500 pM.

[0105] In some embodiments, the plant defense elicitor is an activator of the salicylic acid pathway. In some embodiments, the plant defense elicitor is salicylic acid. In some embodiments, the salicylic acid is present in the composition at a concentration from about 250 pM to about 750 pM.EXAMPLES

[0106] The invention will now be further described based on the following examples. It is to be understood that these examples are intended for illustrative purposes only, and by no means should be construed to be limiting the scope of the invention, which is only defined by the appended embodiments.Example 1: Field assay to evaluate the effect of plant defense elicitors on / ). mi / / / s-in tested corn crops

[0107] Materials and MethodsCorn germplasms: Bt Pioneer® P2089 VYHR, Non-Bt Pioneer® RFG22Sowing date: 9th January 2024. Emergence date 15th January 2024. Harvest date: 9th April 2024.Fertilization (29 / 01 / 2024 - 200 kg / ha).

[0108] Treatments were weekly applications on Mondays of the following in the two corn germplasms:1) Control water + 0.05% w / w Tween® 802) Methyl Jasmonate (MeJA) lOOpM (in a volume equivalent to lOOL / ha) + 0.05% Tween® 80 until 19th February (V6) and 200pM (in a volume equivalent to lOOL / ha) + 0.05% Tween® 80 until the end of the assay.3) Salicylic acid (SA) 500 pM + 0.05% w / w Tween® 80(in a volume equivalent to lOOL / ha)

[0109] Insecticide applications were performed with chlorantraniliprole + lambdacyalothrin in reproductive stage R3 (20 / 03 / 2024, 100 mL / ha).

[0110] The j asmonate pathway activation was monitored with volatile induction.

[0111] Six plants were enclosed together in volatile-emitting-inert oven plastic bags, leaving the pot out of the bag. Six replicates with six plants each were performed for the MeJA treatments. Four replicates with six plants were also performed with non-treated plants. The opening was wrapped and tightened around the stems of the group of plants with a twist tie. Charcoal-fdtered air was pushed into the bag with an air pump and then pulled by a suction pump at a constant rate of 1 L per min. Air leaving the recipient passed through a volatile collection trap (30 mg HayeSep Q) where volatiles were collected. Plants were illuminated from above with white led lamps (light intensity on the plant was 20,000 Im. nr2). Temperature was maintained constant at 25°C. Six system blanks were also performed. After a sampling period of 6 h (between 10 AM and 4 PM), the volatile collection traps were eluted with 150 pL of dichloromethane containing 5 ng / mL of dodecane as internal standard.

[0112] Volatile samples were analyzed by coupled gas chromatography-mass spectrometry(GC / MS) (Agilent 7890 instrument coupled to Agilent 5977 selective mass detector). A DB5MS capillary column was used (0.25-mm i d., film thickness 0.25 pm). Samples (1 pL) were injected at240 °C in a splitless mode. Helium was used as carrier gas at 0.75 mL per min. The column temperature was held at 35 °C for 1 min, and then increased at a rate of 5 °C per min until it reached 100 °C, then 12 °C per min until 230 °C.

[0113] Plants treated with a 100 pM solution released 5 ng / h volatile compounds compared to an average of 1.8 ng / h in the control plants, which gave an indication of the activation of metabolic pathways. Volatiles released by treated plants included significantly more limonene, indol (a key volatile in defense pathways activation), b-famesene and other two homoterpenes.

[0114] Table 1:

[0115] Three plots of each treatment were distributed according to Fig. 1. Each plot consisting of four lines with 50 plants each, totalizing 200 plants per plot.

[0116] Parameters measuredA. Insects screening: Dalbulus maidis incidence was assessed three times a week. D. maidis adults were assessed by counting the number present in the corn stalk of 30 plants per plot.B. Chlorophyl was measured on 5thFebruary and 13thMarch with an AgLeaf Chlorometer, taking measures of ten random plants per plot.C. Plants height was measured on 26thFebruary in VT stage.D. Corn stunting disease symptomatology assessment: 18thMarch. Scale as shown Fig. 2 was used.E. Corn stunting disease sampling for ELISA on 20thMarch.F. Yield.G. Natural enemies’ assessment: Egg parasitoids (the main natural enemies of D. maidis) were assessed using marked sentinel eggs in three plants from each plot. After 72 hs exposure, leaf pieces with sentinel eggs were transferred to the laboratory, stored in petri dishes with humidity until emergence of the parasitoid wasps.

[0117] Results

[0118] In the field assay it was observed that the presence of the vector D. maidis is reduced by 10% in the MeJA primed treatments (Fig. 3). More notably, an increase in chlorophyll content (Fig.4) and in plant height (Fig. 5) was observed in the MeJA primed plants. Particularly, plant height is a very noteworthy symptom in com stunting disease affected plants. Although all plants tested positive for corn stunting disease, visual estimation of symptoms was significantly reduced in Non-Bt MeJA primed plants (Fig. 6).

[0119] Yield was estimated for a hectare after harvest. Plants primed with MeJA and SA had significantly more yield than control ones, particularly in the Non-Bt germplasm, where a 41% increase in yield was achieved for MeJA-primed plants (Fig. 7).

[0120] Parasitism by egg parasitoid wasps was also increased in MeJA primed plants (Fig. 8), being also higher in Non-Bt corn than in Bt corn.

[0121] As it can be seen in the results of the field assay, the treatments with both tested plant defense elicitors were effective in reducing the incidence of D. maidis in corn crops, and particularly in reducing the symptoms associated with corn stunting disease. The results were more significant in Non-Bt com than in Bt com, with MeJA generally exhibiting better results than SA.Example 2: Dose Optimization

[0122] Materials and Methods

[0123] Insect Infestation Protocol

[0124] At the VI growth stage, individual plants were inoculated with five infective Dalbulus maidis adults. The infestation period lasted 96 hours, after which the adults were removed. Plants were then isolated in individual cages to prevent further exposure.

[0125] Treatment Application

[0126] Treatments were initiated 48 hours after the removal of insects. Throughout the experimental period, plants received a fixed water volume at each irrigation event, ensuring no water leakage through the pots. The specifics of each experimental setup, including water volume and duration, are detailed in Table 2.

[0127] Table 2: Treatment Regimen

[0128] Results;

[0129] Results from #E1; Germplasm RFG22 are shown in Fig. 9. Tables 3 and 4 describe aerial and root dry weights, respectively. Tables include Number of observations, Min, Max, Average (Av) and Standard Deviation (SD). Negative control = plants with no infestation; Positive control = Plants with infestation and no treatment.

[0130] Table 3:

[0131] Table 4:

[0132] Results from #E2; Germplasm Brevant 22.6 are shown in Fig. 10. Tables 5 and 6 describe aerial and root dry weights, respectively. Tables include Number of observations, Min, Max, Average (Av) and Standard Deviation (SD). Negative control = plants with no infestation; Positive control = Plants with infestation and no treatment.

[0133] Table 5:

[0134] Table 6:

[0135] Results from #E3; Germplasm RFG 22 are shown in Fig. 11. Tables 7 and 8 describe aerial and root dry weights, respectively. Tables include Number of observations, Min, Max,Average (Av) and Standard Deviation (SD). Negative control = plants with no infestation; Positive control = Plants with infestation and no treatment.

[0136] Table 7:

[0137] Table 8:

[0138] The dose-response results indicate that both MeJA 25 pM and MeJA 50 pM showed positive effects on biomass accumulation in Dalbulus maidis-infested maize plants (Figs. 9-11). While MeJA 50 pM, equivalent to 1.1g of pure compound per hectare, produced the most consistent enhancement of both aerial and root biomass across all germplasms and experiments, the MeJA 25 pM treatment also demonstrated beneficial outcomes, albeit with slightly greater variability.

[0139] This suggests that both concentrations are biologically active and capable of partially restoring growth compromised by herbivore attack. Importantly, the lower dose (25 pM, equivalent to 0.5g / ha) may offer advantages in terms of reduced input cost or minimized off-targetphysiological effects, making it a potentially attractive alternative depending on the application context.

[0140] Dalbulus maidis Abundance in RFG22 under MeJA Treatments

[0141] In cages containing five plants of the germplasm RFG22, the abundance of Dalbulus maidis was evaluated under different concentrations of methyl j asm onate (MeJA) and a positive control. The results revealed a non-linear dose-response pattern based on mean insect counts:• MeJA 2.2 g / ha: 28.5 ± 31.8 (n = 2) — the most effective treatment in reducing Dalbulus abundance.• MeJA 0.5 g / ha: 50.0 ± 39.0 (n = 3) — intermediate effectiveness, but with high variability.• MeJA 1.1 g / ha: 63.4 ± 32.9 (n = 5) — less effective than both lower and higher doses.• Positive control (infested, no treatment): 69.3 ± 17.6 (n = 4) — highest insect abundance observed.

[0142] These findings suggest that the highest dose tested (MeJA 2.2 g / ha) was the most effective at suppressing herbivore pressure. However, considering both biomass improvement and reduction in infestation, both concentrations 25- 50 pM were selected for subsequent field experiments.Example 3: Field assay to evaluate the effect of plant defense elicitors on D.maidis-infested corn crops

[0143] Table 9: Treatments:

[0144] Table 10: List of field assays:

[0145] MeJA was applied weekly from V2-V8 (5 applications), diluted lOOL / Ha

[0146] Results;

[0147] MeJAl. l formulation was tested against control plots across 8 locations, using 6 different corn germplasms, MeJA0.5 was also tested in one location. At each site, two replicate plots per treatment were established randomly, some measuring 4 com lines x 10 meters and others measuring 8 com lines x 10 meters. Between 20-40 plants were individually measured in each plot.

[0148] Table 11:

[0149] MeJA treatment had a positive impact on plant height in 6 out of 7 trials with available data. Maximum height increase was achieved in Assay 6. Assay 10: had a negative impact, with 19% reduction. These results suggest that the treatment generally promotes vegetative growth, although context-dependent variability, and it is probably related to the fact that pest pressure was higher in assay#6 compared to the other ones.

[0150] Overall, treatments had a positive effect on yield in 6 out of 8 reported assays, with only minor losses in 2. Assay#6 had a strong yield boost, but plants in that experiment were severely affected by pests.

[0151] Assay #1: Experimental design is shown in Fig. 12. Only the com plants in the central rows of Brevant 22.6 (Bt) and RFG22 (non-Bt) were monitored. Plants height in V9 stage (AV&SE). As seen in Fig. 13, plants treated with MeJA 1.1 had higher yields, 5.61% in Brevant 22.6 (Bt) and 20.76% more in RFG22 (No-Bt).

[0152] Table 12A:

[0153] Table 12B:

[0154] Assay #2: Experimental design is shown in Fig. 14. Plants from two central rows in each block were monitored for height (measured in V10 stage), and yield. As seen in Fig. 15, plants treated with MeJAl.l yielded 38% more.

[0155] Table 13:

[0156] Assay #3: Experimental design is shown in Fig. 16. Plants from two central rows in each block were monitored for height (measured in VI 1 stage), and yield. Plants treated with MeJA0.5 yielded 37% more than the control treatment. As seen in Fig. 17, plants treated with MeJAl.l yielded 11.9% more than the control treatment.

[0157] Table 14A:

[0158] Table 14B:

[0159] MeJA increased plant’s height and chlorophyll content.

[0160] Assay #6: Experimental design is shown in Fig. 18. Plants from two central rows in each block were monitored for height (measured in VI 1 stage), and yield. As seen in Fig. 19, plants treated with MeJAl.l yielded 134.5% more than control treatment.

[0161] Table 15:

[0162] MeJA increased plant’s height.

[0163] Assay #7: Experimental design is shown in Fig. 20. Plants from two central rows in each block were monitored for height (measured in V9-V10 stage), and yield. As seen in Fig. 21, although plants treated with MeJAl.l where taller, they yielded 1.9% less than control treatment.

[0164] Table 16:

[0165] Assay #9: Experimental design is shown in Fig. 22. Plants from two central rows in each block were monitored for height (measured in V10 stage), and yield. As seen in Fig. 23, plants treated with MeJAl.l where taller, they yielded 9.9% more than control treatment.

[0166] Table 17:

[0167] Assay #10: Experimental design is shown in Fig. 24. Plants from two central rows in each block were monitored for height (measured in V10-V11 stage), and yield. As seen in Fig. 25, although plants treated with MeJAl .1 where shorter, yield was very similar to control treatment, 1.3% more than control treatment.

[0168] Table 18:Example 4: Greenhouse assay to evaluate the effect of plant defense elicitors on D.maidis- infested corn crops

[0169] Corn Germplasms: RFG22 (hereafter referred to as Non-Bt), Brevant 22.6 (hereafter referred to as Bt)

[0170] Sowing Date: June 25, 2024

[0171] End of Assay: October 2, 2024

[0172] Experimental Design: 20 pots (5 L each) per treatment.

[0173] Infestation: All plants were individually infestated at the V2 growth stage with five infective Dalbulus maidis adults per plant. After one week of exposure, the insects were removed, and the plants were maintained under semi-controlled greenhouse conditions (temperature, humidity, and photoperiod) for the duration of the experiment. No physical protection (e.g., cages) was used, except for the negative control.

[0174] Irrigation Management: Controlled irrigation was applied, starting with 100 mL per plant. Plants were watered twice a week until the V4 stage. From V4 onward, irrigation was increased to 200 mL per plant, maintaining the same frequency until the end of the cycle.

[0175] Table 19: Treatments (applied weekly)

[0176] Parameters Measured1. Plant height (measured from the base to the last fully expanded leaf).2. Presence of D. maidis on each treatment.3. Visual assessment of stunting symptoms (leaf chlorosis and reddening), recorded as the proportion of affected plants per block.

[0177] Data Analysis

[0178] All measured parameters were analyzed using analysis of variance (ANOVA) followed by Tukey’s pairwise comparisons to assess significant differences among treatments. Statistical analyses were performed using XLSTAT version 2024.4. 1.

[0179] Results

[0180] Plant’s height:

[0181] Two months after the start of the assay, most plants had reached the V7 stage. In Non-Bt corn, plants treated with MeJA 1.1 were not significantly different from the negative control, and they differed from the positive control (Table 20), while in Bt corn, no treatment was significantly different from the positive control (Table 21).

[0182] Table 20: Tukey’s test pairwise comparisons (Non-Bt com) 29thAugust 2024. Different letters indicate significant differences (p<0.05).

[0183] Table 21: Tukey’s test pairwise comparisons (Bt com) 29thAugust 2024

[0184] By mid-September, most plants had reached the VI 0 developmental stage. In non-Bt corn, salicylic acid (SA) was the only treatment that showed a statistically significant difference compared to the positive control (Table 22). However, SA also differed significantly from the negative control, suggesting an intermediate effect. Additionally, SA was not significantly different from MeJA 1.1.

[0185] In contrast, in Bt com, none of the treatments produced statistically significant differences relative to the positive control (Table 23).

[0186] Table 22: Tukey’s test pairwise comparisons (Non-Bt com) 11thSeptember 2024

[0187] Table 23: Tukey’s test pairwise comparisons (Bt com) 25thSeptember 2024

[0188] The negative control plants were kept isolated in cages until near the end of the assay. As a result, these plants experienced reduced light exposure, which likely contributed to their greater height compared to other treatments. This environmental factor should be considered when interpreting height differences involving the negative control.

[0189] Dalbulus maidis presence:

[0190] Two distinct population peaks of Dalbulus maidis were observed. The first occurred between August 18 and 27, coinciding with the time when most individuals reached the adult stage following inoculation. Treatments showed similar performance in reducing insect’s presence compared to the positive control, with SA treatment being more effective in Non-Bt corn (Fig. 26). Fig. 26 describes Dalbulus maidis counts in August 21 during V6 stage. Bars indicate Sta Error. N=num of observations, Av= average, SD= Standard Deviation.

[0191] Table 24:

[0192] Table 25:

[0193] The second population peak was recorded between September 17 and October 8, with higher psyllid numbers observed in the positive control treatment and the SA treatment (Fig. 27). Fig. 27 describes Dalbulus maidis counts in August 21 during V6 stage. Bars indicate Sta Error.N=num of observations, Av= average, SD= Standard Deviation.

[0194] Table 26:

[0195] Table 27:

[0196] Visual assessment of stunting symptoms

[0197] Chlorosis symptoms — including chlorotic banding, yellowing at the leaf base, and the presence of foliar streaks — were evaluated visually. Plants in the positive control and those treated with MeJA 2.2 exhibited the most severe expression of corn stunt chlorosis symptoms (Fig. 28). Fig. 28 demonstrates visual assessment of stunting symptoms.

[0198] In contrast, the MeJA 1.1 treatment showed the best performance in non-Bt corn, with a notable reduction in visible chlorosis symptoms, suggesting a potential protective or mitigating effect against stunting -related stress.

[0199] Embodiments of the present disclosure:1. A method for alleviating the damaging effects of Dalbulus maidis in a com crop, the method comprising: applying a composition comprising a plant defense elicitor to the com crop, wherein the plant defense elicitor is selected from the group comprising of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway.2. The method of embodiment 1, wherein the plant defense elicitor is an activator of the jasmonic acid pathway.3. The method of embodiment 2, wherein the plant defense elicitor is methyl jasmonate.4. The method of embodiment 3, wherein the methyl jasmonate is applied to the corn crop at a dose from O.Olg / ha to 5 g / ha.5. The method of embodiment 1, wherein the plant defense elicitor is an activator of the salicylic acid pathway.6. The method of embodiment 6, wherein the plant defense elicitor is salicylic acid.7. The method of embodiment 7, wherein the salicylic acid is applied to the com crop at a dose from 0.01 g / ha to 5 g / ha.8. The method of embodiment 1, wherein the plant defense elicitor is present in the composition in a concentration from about 1 pM to about 1000 pM.9. The method of embodiment 2, wherein methyl jasmonate is present in the composition at a concentration from about 1 to about 500 pM.10. The method of embodiment 7, wherein salicylic acid is present in the composition at a concentration from about 250 pM to about 750 pM.11. The method of any one of embodiments 1 to 10, wherein the method comprises applying the plant defense elicitor to the com crop more than once.12. The method of any one of embodiments 1 to 11, wherein the application is to an aerial part of the corn crop.13. The method of any one of embodiments 1 to 12, wherein the corn crop does not produce Bacillus thuringiensis toxins.14. The method of embodiment 1, which is a method to alleviate the damaging effects of Dalbulus maidis in a corn crop, thereby limiting or reducing the damage compared to an untreated control.15. Use of a composition comprising a plant defense elicitor and an agronomically acceptable carrier for alleviating the damaging effects of D. maidis in a com crop, wherein the plant defense elicitor is selected from the group comprising of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway.16. The use of embodiment 15, wherein the plant defense elicitor is present in the composition in a concentration from about 1 pM to about 1000 pM.17. The use of embodiment 15 or 16, wherein the plant defense elicitor is an activator of the jasmonic acid pathway.18. The use of embodiment 17, wherein the plant defense elicitor is methyl j asm onate.19. The use of embodiment 18, the methyl j asm onate is present in the composition at a concentration from about 1 to about 500 pM.20. The use of embodiment 15 or 16, wherein the plant defense elicitor is an activator of the salicylic acid pathway.21. The use of embodiment 20, wherein the plant defense elicitor is salicylic acid.22. The use of embodiment 21, wherein the salicylic acid is present in the composition at a concentration from about 250 pM to about 750 pM.23. The use of any one of embodiments 15 to 22, wherein the agronomically acceptable carrier is an aqueous solution comprising a polysorbate or liquid silicone.24. The use of embodiment 23, wherein the polysorbate is polysorbate 80.25. A method for alleviating the damaging effects of Dalbulus maidis in a com crop, the method comprising: detecting an infection by Dalbulus maidis in the corn crop; and applying an effective amount of a composition comprising a plant defense elicitor to the corn crop; wherein the plant defense elicitor is an activator of the salicylic acid pathway or an activator of the jasmonic acid pathway in the com crop.

Claims

CLAIMS1. A method for alleviating the damaging effects of Dalbulus maidis in a corn crop, the method comprising: applying a composition comprising a plant defense elicitor to the com crop, wherein the plant defense elicitor is selected from the group comprising of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway.

2. The method of claim 1, wherein the plant defense elicitor is an activator of the jasmonic acid pathway.

3. The method of claim 2, wherein the plant defense elicitor is methyl j asm onate.

4. The method of claim 3, wherein the methyl jasmonate is applied to the corn crop at a dose from O.Olg / ha to 5 g / ha.

5. The method of claim 1, wherein the plant defense elicitor is an activator of the salicylic acid pathway.

6. The method of claim 6, wherein the plant defense elicitor is salicylic acid.

7. The method of claim 7, wherein the salicylic acid is applied to the corn crop at a dose from 0.01 g / ha to 5 g / ha.

8. The method of claim 1, wherein the plant defense elicitor is present in the composition in a concentration from about 1 pM to about 1000 pM.

9. The method of claim 2, wherein methyl j asm onate is present in the composition at a concentration from about 1 to about 500 pM.

10. The method of claim 7, wherein salicylic acid is present in the composition at a concentration from about 250 pM to about 750 pM.

11. The method of any one of claims 1 to 10, wherein the method comprises applying the plant defense elicitor to the corn crop more than once.

12. The method of any one of claims 1 to 11, wherein the application is to an aerial part of the corn crop.

13. The method of any one of claims 1 to 12, wherein the corn crop does not produce Bacillus thuringiensis toxins.

14. The method of claim 1, which is a method to alleviate the damaging effects of Dalbulus maidis in a com crop, thereby limiting or reducing the damage compared to an untreated control.

15. Use of a composition comprising a plant defense elicitor and an agronomically acceptable carrier for alleviating the damaging effects of D. maidis in a corn crop, wherein the plant defense elicitor is selected from the group comprising of an activator of the salicylic acid pathway and an activator of the jasmonic acid pathway.

16. The use of claim 15, wherein the plant defense elicitor is present in the composition in a concentration from about 1 pm to about 1000 pM.

17. The use of claim 15 or 16, wherein the plant defense elicitor is an activator of the jasmonic acid pathway.

18. The use of claim 17, wherein the plant defense elicitor is methyl jasmonate.

19. The use of claim 18, the methyl jasmonate is present in the composition at a concentration from about 1 to about 500 pM.

20. The use of claim 15 or 16, wherein the plant defense elicitor is an activator of the salicylic acid pathway.

21. The use of claim 20, wherein the plant defense elicitor is salicylic acid.

22. The use of claim 21, wherein the salicylic acid is present in the composition at a concentration from about 250 pM to about 750 pM.

23. The use of any one of claims 15 to 22, wherein the agronomically acceptable carrier is an aqueous solution comprising a polysorbate or liquid silicone.

24. The use of claim 23, wherein the polysorbate is polysorbate 80.

25. A method for alleviating the damaging effects of Dalbulus maidis in a corn crop, the method comprising: detecting an infection by Dalbulus maidis in the corn crop; and applying an effective amount of a composition comprising a plant defense elicitor to the corn crop; wherein the plant defense elicitor is an activator of the salicylic acid pathway or an activator of the jasmonic acid pathway in the com crop.

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